OPTIMIZATION OF THE HYBRID SULFUR CYCLE FOR HYDROGEN GENERATION

The hybrid sulfur cycle (modified from the Westinghouse Cycle) for decomposing water into oxygen and hydrogen is evaluated. Hydrogen is produced by electrolysis of sulfur dioxide and water mixture at low temperature, which also results in the formation of oxygen and sulfuric acid. The sulfuric acid is decomposed into steam and sulfur trioxide, which at high temperature (1100 K) is further decomposed into sulfur dioxide and oxygen. The presence of sulfur dioxide along with water in the electrolyzer reduces the required electrode potential well below that required for electrolysis of pure–water, thus reducing the total energy consumed by the electrolyzer. Further, using only sulfuric acid for the thermochemical processes minimizes the required chemical stock in the hydrogen plant well below that required for the sulfur–iodine pure thermochemical cycle (SI cycle). In this study, ways to optimize the energy efficiency of the hybrid cycle are explored by varying the electrolyzer acid concentration, decomposer acid concentration, pressure and temperature of the decomposer and internal heat recuperation, based on currently available experimental data for the electrode potential. An optimal cycle efficiency of 43.9% (LHV) appears to be achievable (5 bar, 1100 K and 60 mol–% of H[subscript 2]SO[subscript 4] at the decomposer, 70 w–% of H[subscript 2]SO[subscript 4] at the electrolyzer). However, the ideal cycle efficiency is over 70% (LHV), which leaves room to improve the achievable efficiency with further development. For a maximum temperature of 1200 K, 47% (LHV) appears to be the maximum achievable cycle efficiency (10 bar, 1200 K and 60 mol–% of H[subscript 2]SO[subscript 4] for decomposer, 70 w–% of H[subscript 2]SO[subscript 4] for electrolyzer). The ideal cycle efficiency is over 80% (LHV). Operation under elevated pressures (70 bar or higher) results in minimized equipment size and capital cost, but there is loss in thermal efficiency. However, the loss in efficiency as pressure increases is not large at high temperature (1200 K) compared to that at low temperatures (1000–1100 K). Therefore, high pressure operation would be favored only if we can achieve high temperature. The major factors that can affect the cycle efficiency are reducing the electrode over–potential and having structural materials that can accommodate operation at high temperature and high acid concentration.Korean Science and Engineering Foundation (Post–doctoral Fellowship

Uptake of Fluorescent Iron Oxide Nanoparticles by Oligodendroglial OLN-93 Cells

To investigate the cellular accumulation and intracellular localization of dimercaptosuccinate-coated iron oxide nanoparticles (D-IONPs) in oligodendroglial cells, we have synthesized IONPs that contain the fluorescent dye BODIPY (BP) in their coat (BP-D-IONPs) and have investigated the potential effects of the absence or presence of this dye on the particle uptake by oligodendroglial OLN-93 cells. Fluorescent BP-D-IONPs and non-fluorescent D-IONPs had similar hydrodynamic diameters and -potentials of around 60 nm and -58 mV, respectively, and showed identical colloidal stability in physiological media with increasing particle size and positivation of the -potential in presence of serum. After exposure of oligodendroglial OLN-93 cells to BP-D-IONPs or D-IONPs in the absence of serum, the specific cellular iron content increased strongly to around 1,800 nmol/mg. This strong iron accumulation was lowered for both types of IONPs by around 50 % on exposure of the cells at 4 C and by around 90 % on incubation in presence of 10 % serum. The accumulation of both D-IONPs and BP-D-IONPs in the absence of serum was not affected by endocytosis inhibitors, whereas in the presence of serum inhibitors of clathrin-dependent endocytosis lowered the particle accumulation by around 50 %. These data demonstrate that oligodendroglial cells efficiently accumulate IONPs by an endocytotic process which is strongly affected by the temperature and the presence of serum and that BP-D-IONPs are a reliable tool to monitor by fluorescence microscopy the uptake and cellular fate of D-IONPs

PARK2 Mutation Causes Metabolic Disturbances and Impaired Survival of Human iPSC-Derived Neurons

The protein parkin, encoded by the PARK2 gene, is vital for mitochondrial homeostasis, and although it has been implicated in Parkinson's disease (PD), the disease mechanisms remain unclear. We have applied mass spectrometry-based proteomics to investigate the effects of parkin dysfunction on the mitochondrial proteome in human isogenic induced pluripotent stem cell-derived neurons with and without PARK2 knockout (KO). The proteomic analysis quantified nearly 60% of all mitochondrial proteins, 119 of which were dysregulated in neurons with PARK2 KO. The protein changes indicated disturbances in oxidative stress defense, mitochondrial respiration and morphology, cell cycle control, and cell viability. Structural and functional analyses revealed an increase in mitochondrial area and the presence of elongated mitochondria as well as impaired glycolysis and lactate-supported respiration, leading to an impaired cell survival in PARK2 KO neurons. This adds valuable insight into the effect of parkin dysfunction in human neurons and provides knowledge of disease-related pathways that can potentially be targeted for therapeutic intervention

Ontogenetic oligodendrocyte maturation through gestational iron deprivation: The road not taken

Developmental iron deficiency (dID) models facilitate the study of specific oligodendrocyte (OL) requirements for their progression to a mature state and subsequent contribution to myelination. In the current work, we used the dID model in transgenic mice expressing green fluorescence protein under the CNPase promoter allowing the identification of cells belonging to the oligodendroglial lineage, and the visualization of the entire myelin structure and single OL morphology. The present work evaluates dID effects on OL complexity in different brain areas. Control animals showed an increase in OL complexity both during development and along the anterior–posterior axis. In contrast, dID animals exhibited an initial increase in CNPase+ cells with prevalence of immature-OL (i-OL), an effect later compensated during development by selective death of those i-OL. As a consequence, developmental behavior was impaired in terms of body balance, muscle response, and sensorimotor functions. To explore why i-OL fail to mature in dID, expression levels of transcriptional factors involved in the maturation of the OL lineage were studied. In nuclear fractions, dID animals showed an increase in Hes5, which prevents the maturation of i-OL, and a decrease in Sox10, a positive regulator of OL maturation. The cytoplasmic fractions showed a decrease in Olig1, which is critical for precursor cell differentiation into premyelinating OL. Overall, the expression levels of Hes5, Sox10, and Olig1 in dID conditions correlated with an unfavorable OL maturation profile. In sum, the current results provide further evidence of dID impact on myelination, keeping OL away from the maturational path.Fil: Guitart, María Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; ArgentinaFil: Vence, Marianela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; ArgentinaFil: Correale, Jorge. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia; ArgentinaFil: Pasquini, Juana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; ArgentinaFil: Rosato Siri, María Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; Argentin